K284-6111 prevents the amyloid beta-induced neuroinflammation and impairment of recognition memory through inhibition of NF-κB-mediated CHI3L1 expression

Background: Alzheimer's disease, which is pathologically characterized by an excessive accumulation of amyloid beta (A beta) fibrils, is a degenerative brain disease and the most common cause of dementia. In a previous study, it was reported that an increased level of CHI3L1 in plasma was found in AD patients. We investigated the inhibitory effect of 2-({3-[2-(1-cyclohexen-1-yl) ethyl]-6,7-dimethoxy-4-oxo-3,4-dihydro-2-quinazolinyl} sulfanyl)-N-(4-ethylphenyl) butanamide (K284-6111), an inhibitor of chitinase 3 like 1 (CHI3L1), on memory impairment in A beta(1-42)-infused mice, and microglial BV-2 cells and astrocytes. Methods: We examined whether K284-6111 (3 mg/kg given orally for 4 weeks) prevents amyloidogenesis and memory loss in A beta(1-42)-induced AD mice model. After intracerebroventrical (ICV) infusion of A beta(1-42) for 14 days, the cognitive function was assessed by the Morris water maze test and passive avoidance test. K284-6111 treatment was found to reduce A beta(1-42)-induced memory loss. Results: A memory recovery effect was found to be associated with the reduction of A beta(1-42)-induced expression of inflammatory proteins (iNOS, COX-2, GFAP, and Iba-1) and the suppression of CHI3L1 expression in the brain. Additionally, K284-6111 reduced A beta(1-42)-induced beta-secretase activity and A beta generation. Lipopolysaccharide (LPS)induced (1 mu g/mL) expression of inflammatory (COX-2, iNOS, GFAP, Iba-1) and amyloidogenic proteins (APP, BACE1) were decreased in microglial BV-2 cells and cultured astrocytes by the K284-6111 treatment (0.5, 1, and 2 mu M). Moreover, K284-6111 treatment suppressed p50 and p65 translocation into the nucleus, and phosphorylation of I kappa B in vivo and in vitro. Conclusion: These results suggest that CHI3L1 inhibitor could be an applicable intervention drug in amyloidogenesis and neuroinflammation, thereby preventing memory dysfunction via inhibition of NF-kappa B.